Ensure SPANK prolog and epilog run without an explicit PlugStackConfig.

If not set, the plugstack option will be populated from
get_extra_conf_path() instead, which means these direct tests on
the option will fail and the SPANK prolog/epilog will not run.

Regression from abd4db7 where the default option was no longer
always filled in.

Bug 9081.

Signed-off-by: Tim McMullan <mcmullan@schedmd.com>

NEWS

@@ -7,6 +7,7 @@ documents those changes that are of interest to users and administrators.
  -- select/cray_aries - Correctly remove jobs/steps from blades using NPC.
  -- Fix false positive oom-kill events on extern step termination when
     jobacct_gather/cgroup configured.
+ -- Ensure SPANK prolog and epilog run without an explicit PlugStackConfig.
 
 * Changes in Slurm 20.02.6
 ==========================

src/plugins/prep/script/prep_script_slurmd.c

@@ -74,7 +74,6 @@ extern int slurmd_script(job_env_t *job_env, slurm_cred_t *cred,
 	char *path = is_epilog ? slurmctld_conf.epilog :
 				 slurmctld_conf.prolog;
 	char **env = _build_env(job_env, cred, is_epilog);
-	struct stat stat_buf;
 	int status = 0, rc;
 	uint32_t jobid = job_env->jobid;
 	int timeout = slurmctld_conf.prolog_epilog_timeout;
@@ -93,7 +92,7 @@ extern int slurmd_script(job_env_t *job_env, slurm_cred_t *cred,
 	 *   If both "script" mechanisms fail, prefer to return the "real"
 	 *   prolog/epilog status.
 	 */
-	if (conf->plugstack && (stat(conf->plugstack, &stat_buf) == 0))
+	if (spank_plugin_count())
 		status = _run_spank_job_script(name, env, jobid);
 	if ((rc = run_script(name, path, jobid, timeout, env, job_env->uid)))
 		status = rc;

src/slurmd/slurmd/req.c

@@ -5227,7 +5227,6 @@ _rpc_complete_batch(slurm_msg_t *msg)
 static void
 _rpc_terminate_job(slurm_msg_t *msg)
 {
-	bool		have_spank = false;
 	int             rc     = SLURM_SUCCESS;
 	kill_job_msg_t *req    = msg->data;
 	uid_t uid = g_slurm_auth_get_uid(msg->auth_cred);
@@ -5367,19 +5366,14 @@ _rpc_terminate_job(slurm_msg_t *msg)
 						uid);
 	}
 
-	if ((nsteps == 0) && !conf->epilog) {
-		struct stat stat_buf;
-		if (conf->plugstack && (stat(conf->plugstack, &stat_buf) == 0))
-			have_spank = true;
-	}
 	/*
 	 *  If there are currently no active job steps and no
 	 *    configured epilog to run, bypass asynchronous reply and
 	 *    notify slurmctld that we have already completed this
 	 *    request. We need to send current switch state on AIX
 	 *    systems, so this bypass can not be used.
 	 */
-	if ((nsteps == 0) && !conf->epilog && !have_spank) {
+	if ((nsteps == 0) && !conf->epilog && !spank_plugin_count()) {
 		debug4("sent ALREADY_COMPLETE");
 		if (msg->conn_fd >= 0) {
 			slurm_send_rc_msg(msg,